Sugar-Responsive Layer-by-Layer Film Composed of Phenylboronic Acid-Appended Insulin and Poly(vinyl alcohol)

Previous studies have shown that reversible chemical bond formation between phenylboronic acid (PBA) and 1,3-diol can be utilized as the driving force for the preparation of layer-by-layer (LbL) films. The LbL films composed of a PBA-appended polymer and poly(vinyl alcohol) (PVA) disintegrated in the presence of sugar. This type of LbL films has been recognized as a promising approach for sugar-responsive drug release systems, but an issue preventing the practical application of LbL films is combining them with insulin. In this report, we have proposed a solution for this issue by using PBA-appended insulin as a component of the LbL film. We prepared two kinds of PBA-appended insulin derivatives and confirmed that they retained their hypoglycemic activity. The LbL films composed of PBA-appended insulin and PVA were successfully prepared through reversible chemical bond formation between the boronic acid moiety and the 1,3-diol of PVA. The LbL film disintegrated upon treatment with sugars. Based on the results presented herein, we discuss the suitability of the PBA moiety with respect to hypoglycemic activity, binding ability, and selectivity for D-glucose.